Exogenous hydrogen peroxide as a possible messenger for the stimulation effect of magnetized physiological solution...

The dual effect of magnetized physiological solution (MPS) on snail heart muscle contractility (muscle relaxation and stimulation of heartbeat) was shown previously. The MPS-induced relaxation of the heart muscle has been explained by activation of cGMP-dependent Ca(2+) effluxes from the muscle; however, the mechanism of the stimulating effect of MPS on heartbeat remains unclear. As in the presence of paramagnetic oxygen molecules, magnetic fields could generate the exogenous reactive oxygen species such as hydrogen peroxide (H(2)O(2)), we hypothesize that H(2)O(2) may play a role as the possible messengers through which the activation effect of MPS on heartbeat is realized. To test this hypothesis, the dose-dependent effects of exogenous H(2)O(2) on heart muscle contractility and (45)Ca uptake were studied. Here we compared the obtained data with the previous results of the effects of MPS on heart muscle contractility and (45)Ca uptake. We found that exogenous H(2)O(2) and MPS have similar effects on Na(+)-K(+) pump-induced transient inhibition of muscle contractility and (45)Ca uptake. The Na(+)-K(+) pump-induced depression of H(2)O(2)-sensitivity of muscle contractility is determined by activation of Ca(2+) efflux from the cell. On the basis of these data we suggest the exogenous H(2)O(2) as a possible messenger through which the stimulation effect of MPS on heart muscle is realized.